in an electroscope which charges transfer from where to where and how does it work
 

Electroscope is a device that is used for detecting whether an object is charged or uncharged. It also determines the type of charge.

As you can see from the picture there is a metal (conductor knob) and a metal rod attached to this knob. Gold leaves are at the bottom of the rod. Electroscopes are placed in a glass case to diminish the effects of wind and ions in the air.

In general an electroscope works on the principle of charging by induction. When we bring a charged object near the electroscope metal knob, opposite charge gets induced in the metal knob, and from there to the gold leaf. On acquiring the charge, the gold leaf separates out. The metal leaves repel each other showing that they carry similar charges. In this manner, an electroscope can detect if an object carries a charge.

The distance to which the leaves spreads depends on the amount of charge the body possess.

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